Field
Aspects of the present invention generally relate to data communication technology for performing streaming distribution to transmit and receive content data in real time.
Description of the Related Art
In recent years, there is provided a data communication technology for distributing content data in a streaming format including audio data, and video data and so on in real time to users in a network camera or a video conference system or the like. By such the data communication technology, users can play back the received content data while at the same time receiving the content data.
Further, Hypertext Transport Protocol (HTTP) live streaming (Internet Engineering Task Force (IETF) draft HTTP Live Streaming draft-pantos-http-live-streaming-09), and Moving Picture Experts Group (MPEG)-dynamic adaptive streaming over HTTP (DASH) (ISO/IEC 23009-1) and others as the data communication technology are standardized. In these standards, the transmission apparatus generates a plurality of pieces of segment data by dividing content data such as video data or audio data at predetermined time intervals. Furthermore, the transmission apparatus transmits metadata (referred to as a playlist) containing location information or reproduction order of each generated segment data to the receiving apparatus. The receiving apparatus acquires the segment data based on the location information and the reproduction order of each segment data, which is listed in the received playlist. In this manner, with each of the above-described standards, streaming of the content data is enabled by transmitting and receiving playlists and segment data continuously at predetermined time intervals between the transmission apparatus and the receiving apparatus.
Further, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2012-514276 discusses a method for enabling selection of a media file to be acquired on the receiving apparatus side by the transmission apparatus providing the receiving apparatus for a playlist file of content (hereinafter referred to as a playlist) separately from the content. The media file refers to a file generated by segmenting the content. Further, the playlist is information used by the receiving apparatus to receive media files, which are generated by dividing the content into a plurality of parts, from the transmission apparatus.
The method discussed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) no. 2012-514276 is that the receiving apparatus transmits acquisition requests of playlists (hereinafter, playlist requests) in a periodic manner. In addition, if the received playlist has not been updated in response to the playlist request, a transmission period of the playlist requests will be changed.
However, the method discussed in Japanese Unexamined Patent Application Publication (Translation of PCT) no. 2012-514276 is that the transmission apparatus can transmit only a playlist that has been generated and updated prior to the playlist request, in response to the playlist request received from the receiving apparatus. Consequently, when the transmission apparatus generates and updates a playlist immediately after receiving a playlist request from the receiving apparatus, the transmission apparatus cannot transmit the latest playlist generated and updated until receiving a next playlist request from the receiving apparatus. In this manner, in the conventional technology, there is an issue that the transmission apparatus cannot control a transmission timing of the playlist, because a case of acquiring the latest playlist immediately after receiving the playlist request from the receiving apparatus is not considered.